Axle cooling using hydraulic return oil

Abstract

A work vehicle includes a frame and an axle assembly coupled to the frame, including a first axle shaft and coil substantially disposed in an axle housing. A first wheel couples to the first axle shaft of the axle assembly. An axle lubricating fluid is disposed within the axle housing. A cooling circuit fluidly coupled to the axle assembly circulates cooling fluid therethrough. The coil conducts cooling fluid through the first axle housing separately from the lubricating fluid. A cooling fluid circuit is selectively fluidly coupled to the first coil to circulate the cooling fluid therethrough.

What is claimed is: 
     
       1. A work vehicle comprising:
 a frame; 
 a first axle assembly coupled to the frame and including a first axle shaft, a second axle shaft and a first axle housing, wherein the first and second axle shaft and a first coil are disposed substantially within the first axle housing; 
 a first wheel coupled to the first axle shaft and a second wheel coupled to the second axle shaft of the first axle assembly; 
 a second axle assembly coupled to the frame and including a third axle shaft, a fourth axle shaft and a second axle housing, wherein the third and fourth axle shaft and a second coil are disposed substantially within the second axle housing; 
 a third wheel coupled to the third axle shaft and a fourth wheel coupled to the fourth axle shaft of the second axle assembly; 
 an axle lubricating fluid disposed within the first and second axle housing, the first coil is configured to conduct cooling fluid through the first axle housing and the second coil is configured to conduct cooling fluid through the second axle housing, the first and second coils maintaining the cooling fluid separate from the lubricating fluid; 
 a cooling fluid circuit having a pump selectively fluidly coupled to the first coil and the second coil to circulate the cooling fluid therethrough wherein flow passing from the pump will flow through at least one vehicle control component and the coils unless diverted by a pressure relief valve in parallel with at least one of the coils; and 
 wherein the pressure relief valve is fluidly coupled in parallel to at least one of the first and second coil downstream from a heat exchanger. 
 
     
     
       2. A work vehicle comprising:
 a frame; 
 a first axle assembly coupled to the frame and including a first axle shaft, a second axle shaft and a first axle housing, wherein the first and second axle shaft and a first coil are disposed substantially within the first axle housing; 
 a first wheel coupled to the first axle shaft and a second wheel coupled to the second axle shaft of the first axle assembly; 
 a second axle assembly coupled to the frame and including a third axle shaft, a fourth axle shaft and a second axle housing, wherein the third and fourth axle shaft and a second coil are disposed substantially within the second axle housing; 
 a third wheel coupled to the third axle shaft and a fourth wheel coupled to the fourth axle shaft of the second axle assembly; 
 an axle lubricating fluid disposed within the first and second axle housing, the first coil is configured to conduct cooling fluid through the first axle housing and the second coil is configured to conduct cooling fluid through the second axle housing, the first and second coils maintaining the cooling fluid separate from the lubricating fluid; 
 a cooling fluid circuit having a pump selectively fluidly coupled to the first coil and the second coil to circulate the cooling fluid therethrough wherein flow passing from the pump will flow through at least one vehicle control component and the coils unless diverted by a pressure relief valve in parallel with at least one of the coils; and 
 wherein the circuit includes the pump, a reservoir and heat exchanger oriented such that flow from the pump will travel from the pump through the heat exchanger and then through the coils before returning to the reservoir unless diverted by one of a thermal bypass valve or the pressure relief valve. 
 
     
     
       3. The work vehicle of  claim 2 , wherein the pressure relief valve is fluidly coupled to the first and second coil. 
     
     
       4. The work vehicle of  claim 1 , wherein the vehicle control component is a brake valve configured to provide hydraulic pressure required to operate brakes of the work vehicle. 
     
     
       5. The work vehicle of  claim 4 , wherein the cooling fluid circuit further comprises a fan downstream from the brake valve. 
     
     
       6. The work vehicle of  claim 5 , further comprising a heat exchanger associated with the fan that is selectably fluidly coupled to the cooling fluid circuit. 
     
     
       7. The work vehicle of  claim 6 , wherein a thermal bypass valve is fluidly disposed in the fluid path between the fan and the heat exchanger upstream from the coils and configured when activated to bypass flow around the heat exchanger toward the coils. 
     
     
       8. A work vehicle comprising:
 a frame; 
 a first axle assembly coupled to the frame and including a first axle shaft, a second axle shaft and a first axle housing, wherein the first and second axle shaft and a first coil are disposed substantially within the first axle housing; 
 a first wheel coupled to the first axle shaft and a second wheel coupled to the second axle shaft of the first axle assembly; 
 a second axle assembly coupled to the frame and including a third axle shaft, a fourth axle shaft and a second axle housing, wherein the third and fourth axle shaft and a second coil are disposed substantially within the second axle housing; 
 a third wheel coupled to the third axle shaft and a fourth wheel coupled to the fourth axle shaft of the second axle assembly; 
 an axle lubricating fluid disposed within the first and second axle housing, the first coil is configured to conduct cooling fluid through the first axle housing and the second coil is configured to conduct cooling fluid through the second axle housing, the first and second coils maintaining the cooling fluid separate from the lubricating fluid; and 
 a cooling fluid circuit is fluidly coupled to the first coil and the second coil to circulate the cooling fluid therethrough wherein the circuit includes a pump, reservoir and heat exchanger oriented such that flow from the pump will travel from the pump through the heater exchanger and then through coils before returning to the reservoir unless diverted by one of a thermal bypass valve or a pressure relief valve. 
 
     
     
       9. The work vehicle of  claim 8 , wherein the pressure relief valve is fluidly coupled in parallel with at least one of the first and second coil downstream of the heat exchanger. 
     
     
       10. The work vehicle of  claim 8 , wherein the first coil and the second coil are coupled in parallel. 
     
     
       11. The work vehicle of  claim 10 , wherein the pressure relief valve is fluidly coupled to the first and second coil. 
     
     
       12. The work vehicle of  claim 8 , wherein the cooling fluid circuit further comprises a brake valve configured to provide hydraulic pressure required to operate brakes of the work vehicle. 
     
     
       13. The work vehicle of  claim 12 , wherein the cooling fluid circuit further comprises a fan downstream from the brake valve. 
     
     
       14. The work vehicle of  claim 13 , wherein the heat exchanger is associated with the fan. 
     
     
       15. The work vehicle of  claim 14 , wherein the thermal bypass valve is fluidly disposed between the fan and the heat exchanger to selectively bypass flow around the heat exchanger toward the coils.